docs: def unload(filename):
      """
      Unload a SPICE kernel.
  
      http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/unload_c.html
  
      :param filename: The name of a kernel to unload.
      :type filename: str
      """
      if isinstance(filename, list):
          for f in filename:
              libspice.unload_c(stypes.stringToCharP(f))
          return
      filename = stypes.stringToCharP(filename)
      libspice.unload_c(filename)